So playing a Priest is certainly from start of Ego Draconis to the end of FoV doable, even on nightmare mode
Not that this build is the most powerful one. I think not. I believe the Ranger build is the most powerful character.
But I love it to use non-Priest skill via skillpoints on equipment, especially Yewellery items are really fantastic pieces of great help !!!
And facing Raze, without some ranger skill(Stun Arrows) and warrior skill(Thousand Strikes, Wirlwind and/or Fatality(via Creature)) ... I believe this battle was almost impossible ... maybe with Summon Demon + Creature full upgraded and I constantly pulling the levers 'off' ? But Hide in Shadows has it's cooldown time and the Walking Armors sparring my way to see the lever(s) ! Really not simple, if you ask me
I have tried Priest skill on the Walking Armors : Fear works and Blind too, but this last one helps a little since that chamber produce so many of them

...
Charm didn't work on the Walking Armors ... and I can't Blind Raze (but that would be too easy then

!)
Maybe Curse can be a good skill here, but I choose to not invest in this skill until FoV, because in FoV many extra skillpoints should come my way

... then it's time to invest in Curse .
and Way of the Wise Wizard ... .